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Running ActiveMQ 5.4.0. I have a group of users that subscribe and publish to each other on various topics through a common ActiveMQ JMS provider. After a while of activity, the ActiveMQ console starts displaying 

INFO|USAGE MANAGER memory limit reached. Stopping producer (ID ...... to prevent flooding topic .....

This message occurs repeatedly for various topics. I know that in some cases, some messages are never delivered. None of the producers on the 'net' are implementing any kind of flow control. They just send and forget. Obviously, some of the producers are being blocked, but most eventually break free. I believe the topics are non-durable/non-persistent.

I'm just using the default activemq configuration. So, how best to fix this problem? Is it wise to disable flow control and how?

eebbesen
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Maxx
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1 Answers1

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If you're using the default ActiveMQ configuration, flow control is on. This is why you're getting those messages.

If you don't want to use flow control you could do something like this:

<policyEntry topic="myTopic" producerFlowControl="false">

What this will do is use as much memory as ActiveMQ has to give you. Be aware, however, that at some point ActiveMQ will start spooling messages through the disk if it thinks you could cause problems for other queues, etc - this will effect performance because it's hitting the disks. This is completely separate from persistence. However if you have set a reasonable heap limit for java on startup in comparison to your total data needs, you should be ok.

Note that if you want to tell it not to spool through the disk, you do have to use flow control and have to set a max in memory size such as:

<policyEntry topic="myTopic" producerFlowControl="true" memoryLimit="200mb">
    <pendingQueuePolicy>
    <vmQueueCursor/>
</pendingQueuePolicy>
</policyEntry>

That would not use the disk, and block producers when the memoryLimit is hit. Again, you should be able to tailor this so it works for your configuration.

For more info on flow control: http://activemq.apache.org/producer-flow-control.html

Brian Roach
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  • Thanks, Brian, for your response. So, in JMS if you have several subscribers for one topic, and one of the subscribers fails to receive a message for some reason will that message live in the broker forever? In such cases, would a time-to-live option be best used on the producer side? – Maxx Mar 13 '11 at 21:15
  • @Maxx - To be honest, I'm not sure. I recently started working with ActiveMQ again after about 1.5 years away from it, and a lot has changed. I just knew a bit about your problem because it was similar to one we just had with queues. I'm currently not using topics at all. – Brian Roach Mar 13 '11 at 21:18
  • I have find this out too. and very easy to implement. @BrianRoach, is it possible to change the configuration and get them in the server without restarting activemq? like hotswap? – DarthVader Nov 01 '11 at 21:03